I have a dog faced puffer who is about 4 1/2 in. He used to share the tank with a blenny who died recently from old age. My puffer used to come out and beg for food and eat while I was in the room. Now he seems depressed and won't eat while I'm around, so I'm not sure if he has been eating. The water quality is great, so I'm really confused. He likes to engage me if I'm i the room, so I think he's just lonely, as opposed to being sick. Does anyone know what else could be wrong? If he's lonely, what kind of fish should I add? One salesperson recommended a lion fish or a trigger. Another person said that either of those would be a bad idea.